This project will develop a rapid method for isolating and labeling granulocytes with gamma-emitting radionuclides such as Tc99m and In111 with a high labeling yield, under aseptic conditions and with preservation of cell viability. Reinjection of labeled cells will be used to detect and localize inflammatory foci and intravascular clots by scintillation camera or scanner. The specific objectives of the research include: (1) the design and formulation of twelve new radiopharmaceuticals which bind irreversibly to granulocytes, particularly lipophilic chelating agents such as 8-hydroxyquinoline and its analogues; (2) measurement of cell tagging of new agents in vitro with granulocyte suspensions; (3) evaluation of labeled granulocytes in experimental animals with induced bacterial and chemical abscesses and femoral venous thrombi; (4) clinical trial of the best radiopharmaceuticals for granulocyte labeling in selected patients for localization of abscess and thrombi by radioisotopic imaging, in comparison with current agents.